The present invention relates, in general, to electronics, and more particularly, to methods of forming semiconductor devices and structure.
In the past, the electronics industry utilized light emitting diodes (LEDs) for a variety of applications. Improvements in the quality and efficiency of light emitting diodes (LEDs) facilitated the use of LEDs in automotive lighting applications such as for brake lights and taillights. Further advances in LEDs facilitated the use for more traditional AC lighting applications such as traffic lights, fluorescent lights, street lights and other lighting application. Typical control systems for LED applications converted an AC waveform into a DC voltage and used this DC voltage to power the LEDs. Systems to control LED are disclosed in U.S. Pat. No. 6,285,139, issued to Mohamed Ghanem on Sep. 4, 2001, and U.S. Pat. No. 6,989,807, issued to Johnson Chiang on Jan. 24, 2006. Most such LED control systems had a high cost. It is desirable to configure the each LEDs system to control the power factor in order to reduce operating costs. It is also desirable to keep the costs very low.
Accordingly, it is desirable to have an LED control system is simple to design, that has a low cost, and that controls the power factor to a substantially unity value.
For simplicity and clarity of the illustration, elements in the figures are not necessarily to scale, and the same reference numbers in different figures denote the same elements. Additionally, descriptions and details of well-known steps and elements are omitted for simplicity of the description. As used herein current carrying electrode means an element of a device that carries current through the device such as a source or a drain of an MOS transistor or an emitter or a collector of a bipolar transistor or a cathode or anode of a diode, and a control electrode means an element of the device that controls current through the device such as a gate of an MOS transistor or a base of a bipolar transistor. Although the devices are explained herein as certain N-channel or P-Channel devices, a person of ordinary skill in the art will appreciate that complementary devices are also possible in accordance with the present invention. It will be appreciated by those skilled in the art that the words during, while, and when as used herein are not exact terms that mean an action takes place instantly upon an initiating action but that there may be some small but reasonable delay, such as a propagation delay, between the reaction that is initiated by the initial action.